1) The present invention relates to the class of automated devices generally referred to as Cartesian robots that are capable of orthogonal two-axis movement, and more particularly to such devices that because of their design and configuration provide broader applicability and permit the use of lighter weight structural elements to obtain equivalent robustness.
2) Cartesian robots are widely used in applications that fit a rectangular work envelope. Such uses include simple assembly operations, dispensing, inspection and loading and unloading of, for example, case packaging machines and the like. Such devices are generally considered a low cost robotic alternative, are relatively easy to program and are viewed as being highly precise because of their linear-motion geometry. As a consequence, they are often built into other machinery and are widely used in xe2x80x9cpick and placexe2x80x9d operations. While highly useful such devices are considered to require large areas in which to operate even though the whole space is not used and they require the largest surface area of any robotic device. Furthermore, they tend to be highly robust devices that are not easily rotated or otherwise moved to increase their effective work envelope due to the requirement that they include a plurality of drive devices or motors that are often located at the extremes of their various moving axes.
3) Because of their versatility and broad usage, there exists a plethora of prior art describing a wide variety of Cartesian robotic devices. Among this prior art are: U.S. Pat. No. 5,611,248 issued Mar. 17, 1998 that describes a two-axis robot comprising a pair of coupling belts, one endless and one fixed to a slide, both driven by a pair of opposing coaxially located drive motors; and U.S. Pat. No. 5.063,334 issued Nov. 5, 1991 that describes an orthogonal two-axis moving apparatus comprising a single coupling belt driven by motors located at the opposing extremities of one of two orthogonal guide members. While both of these devices provide highly useful apparatus, they each have shortcomings that will become apparent upon a reading of and in the course of the presentation of the description of the novel Cartesian robot described herein. Most importantly, the Cartesian robot of the present invention is of lower cost to manufacture and, because of the reduced weight of many of its components, a result of its unique design, reduces the need for heavy duty and fixed installation and permits increased speed of operation.
4) It is therefore an object of the present invention to provide an enhanced Cartesian robot that is of lower cost to produce by virtue of its design.
5) It is another object of the present invention to provide a Cartesian robot that is significantly lighter and more manageable than similar prior art such devices.
6) The apparatus of the present invention comprises a two-axis Cartesian robot including a first guide member which extends along one direction and is attached to a stationary position, a hollow carriage which is translatable along the first guide member, and is penetrated by a second orthogonal guide member, thereby allowing the carriage to move along the first guide member on a track and relative to the second guide member. First and second idler rollers are rotatably supported on two ends of the second guide member, a third idler roller is rotatably supported on one end of the first guide member, and intermediate idler rollers are rotatably supported on four corner portions of the hollow carriage and all drive mechanisms are orthogonally positioned and located at the first guide member stationary position. A first guide member drive belt driven by a drive mechanism located at the stationary position is provided and has two ends of which are fixed to the second or opposing end of the first guide member and looped in a cross shape on the first to third idler rollers and the four intermediate idler rollers. A second guide member drive belt driven by a second drive mechanism located at the stationary point and orthogonal to the first drive mechanism has two ends fixed to opposing extremities of the hollow carriage. The second guide member penetrates the hollow carriage and is carried by guide rollers or casters along a track that forms a part of the first guide member. The symmetrical alignment of the drive forces with respect to the centerline of the hollow carriage reduces torque induced during operation and the co-location of the independent drive mechanisms at one end of the robot permits the provision of a mechanism to rotate the entire assembly about a third axis located at the stationary position and further permits reduction in the size and weight of the individual drive mechanisms and other components.